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Daniel Abrecht

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Registered: 2017-05-21

Posts: 1  

How to setup a devuan libvirt-lxc container

Install libvirt

daniel@colibri:/# apt-get install libvirt-bin libvirt0 libvirt-daemon cgroupfs-mount

Bootstrap your devuan container

root@colibri:~# mkdir /vm
root@colibri:~# cd /vm
root@colibri:/vm# debootstrap jessie my_lxc_container http://auto.mirror.devuan.org/merged

(chroot) Some necessary configuration changes inside the new container

For the next steps, you must chroot into your lxc container:

root@colibri:/# chroot my_lxc_container/

Make sure you don't perform any of the following steps outside the chroot!

(chroot) Change the password

root@colibri:/# passwd
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully

(chroot) Set your language

root@colibri:/# apt-get install locales
root@colibri:/# dpkg-reconfigure locales

(chroot) Set the host name

root@colibri:/# echo "Your-new-hostname" > /etc/hostname

(chroot) Disable spawning of non-existant consoles

We'll only define one console later in libvirt, which will only create one tty, namely /dev/pts/0, but the container tries to spawn 6 consoles. To change this, we need to comment out all lines which look like ":23:respawn:/sbin/getty". Only the first line shouldn't be commented out. The following command will do that for you:

root@colibri:/# sed -i 's|.:23:respawn:/sbin/getty|#\0|' /etc/inittab

(chroot) Disable pam_loginuid.so

pam_loginuid.so tries try to write to /proc/self/loginuid on login if it is enabled in the kernel, but it's mounted readonly in libvirt-lxc, which may cause the login attemp to fail. So we just comment it out:

root@colibri:/# sed -i 's/session    required     pam_loginuid.so/#\0/' /etc/pam.d/*

(chroot) Allow libvirts' console (/dev/pts/0) for logins

Just add pts/0 to /etc/securetty:

root@colibri:/# echo 'pts/0' >> /etc/securetty

(chroot) Disable checksum offloading & configure dhcp

UDP-Checksum offloading may cause invalid UDP checksums, which may cause dhclient to fail. Disable it using ethtool and /etc/network/interfaces:

root@colibri:/# apt-get install ethtool
root@colibri:/# cat > /etc/network/interfaces <<EOF
source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
  pre-up ethtool --offload eth0 rx off tx off

EOF

You can now leave the changeroot using "exit" or CTRL+D.

Create the XML Config for your libvirt-lxc container

Here is an example config. The rest of this tutorial assums it to be in /var/virt/my_lxc_container.xml The following config assums that you want to use the network config "default" for this domain and your LXC Countainer root directory is at /vm/my_lxc_container/. You may need to start the default network first, or change/add/remove settings if you want a different configuration.

<domain type='lxc'>
  <name>my_lxc_container</name>
  <memory unit='GiB'>1</memory>
  <os>
    <type>exe</type>
    <init>/sbin/init</init>
  </os>
  <vcpu>1</vcpu>
  <features>
    <privnet/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <filesystem type='mount'>
      <source dir='/vm/my_lxc_container/' />
      <target dir='/' />
    </filesystem>
    <interface type='network'>
      <mac address='00:f0:12:34:56:78'/>
      <source network='default'/>
    </interface>
    <console type='pty' />
  </devices>
</domain>

Define the domain for your libvirt LXC container using your XML config

root@colibri:/vm# virsh -c lxc:/// define /var/virt/my_lxc_container.xml
Domain my_lxc_container defined from /var/virt/my_lxc_container.xml

Start your default network interface & set it as autostart

root@colibri:/vm# virsh net-start default
root@colibri:/vm# virsh net-autostart default
Network default marked as autostarted

Start your container

root@colibri:/vm# virsh -c lxc:/// start my_lxc_container
Domain my_lxc_container started

Open the console of your Container and login

root@colibri:/vm# virsh -c lxc:/// console my_lxc_container

Congratulations, you just configured your first libvirt-lxc container.

Last edited by Daniel Abrecht (2017-06-02 22:26:41)